The invention relates to treatment of tissues, and more particularly to methods and systems for treatment of tissues using ultrasound.
Undesirable tissues such as subcutaneous fat, visceral fat, lipomas and tumors may be non-invasively treated using ultrasound. Typically, focused ultrasound with a thermal or cavitational treatment is used for treatment of such tissues. In a thermal treatment, the ultrasound power is concentrated for a short continuous duration and the tissue is heated by intense vibrations. In a cavitational treatment, ultrasound energy is used to vibrate the tissues in a relatively less intense manner in order to damage the cells. The damaged cells may subsequently die via a necrotic or apoptotic cell death. During ablation, damage to the tissues may be achieved via a combination of thermal and cavitational effects by adjustment of the ultrasound parameters by carefully selecting the ultrasound transducer frequency. For example, a transducer with a frequency range from about 1 MHz to about 2 MHz may be adjusted to run in a low duty cycle pulsed mode for a predominantly cavitational effect. However, if the duty cycle is increased to a continuous wave (CW) the effect may be predominantly thermal.
The cavitation threshold for various tissues is different. Hence, for a cavitational treatment it is desirable to determine the tissue types that are to be treated and adjust the treatment accordingly. For example, in case of cosmetic ablation of adipose tissue, it is desirable to have a precise determination of the location of fat layer. A precise determination of the location of the tissues is required for locating the fat layer for ablation as well as for post ablative examination of the residual layer.
Therefore, it would be desirable to provide a method for automatically identifying and segmenting different tissue types in ultrasound images for performing procedures, such as ablation.